Tensioner with Anodized Friction Surface

Abstract

A tensioner comprising a base having a shaft, an arm pivotally engaged with the shaft, a pulley journalled to the arm, a torsion spring engaged between the arm and the base, a damping element for damping an arm movement, the damping element frictionally engaged with the arm upon a pressing engagement by the torsion spring, the arm having an anodic oxide surface finish, and the damping element frictionally engaging the anodic oxide surface finish.

We claim: 
     
         1 . A tensioner comprising:
 a base having a shaft projecting therefrom;   an arm pivotally engaged with the shaft, a pulley journalled to the arm;   a torsion spring engaged between the arm and the base;   a damping element for damping an arm movement, the damping element frictionally engaged with the arm upon a pressing engagement by the torsion spring;   the arm having an anodic oxide finish on an inner surface; and   the damping element frictionally engaging the anodic oxide finish.   
     
     
         2 . The tensioner as in  claim 1 , wherein the arm is die cast aluminum. 
     
     
         3 . The tensioner as in  claim 1 , wherein the base comprises an alloy of aluminum. 
     
     
         4 . The tensioner as in  claim 1 , wherein the base is die cast aluminum. 
     
     
         5 . The tensioner as in  claim 1  further comprising a seal between the arm and the base. 
     
     
         6 . The tensioner as in  claim 1 , wherein the pulley is journalled on a ball bearing. 
     
     
         7 . A tensioner comprising:
 a base comprising die cast aluminum;   an arm comprising die cast aluminum pivotally engaged with the base, a pulley journalled to the arm;   a torsion spring engaged between the arm and the base;   a damping element for damping an arm movement, the damping element frictionally engaged with the arm upon a pressing engagement by the torsion spring; and   the arm having an anodic oxide surface finish, the damping element engaging the anodic oxide surface finish.   
     
     
         8 . The tensioner as in  claim 7 , wherein the base comprises an anodic oxide surface finish. 
     
     
         9 . A tensioner comprising:
 a base comprising die cast aluminum, a shaft projecting from the base;   an arm comprising die cast aluminum pivotally engaged with the shaft, a pulley journalled to the arm;   a torsion spring engaged between the arm and the base;   a damping element for damping an arm movement, the damping element frictionally engaged with the arm upon a pressing engagement by the torsion spring; and   the arm and the base each having an anodic oxide surface finish, the damping element frictionally engaging the anodic oxide surface finish.   
     
     
         10 . The tensioner as in  claim 9  further comprising a seal between the arm and the base. 
     
     
         11 . The tensioner as in  claim 9 , wherein the pulley is journalled on a ball bearing.